Ha-ras oncogene-induced Stat3 phosphorylation enhances oncogenicity of the cell

Hsuan Heng Yeh, Raghavaraju Giri, Tsuey Yu Chang, Cheng Yang Chou, Wu Chou Su, Hsiao Sheng Liu

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The ras oncogene needs a second factor to induce transformation and tumorigenicity of the cell. In this study, we show that mouse fibroblast 7-4-Stat3C cells overexpressing both Ha-rasval12 oncogene and active-form Stat3 (Stat3C) showed higher colony formation in soft agar and xenograft tumor growth in BALB/c mice. Further studies show that both serine-727 and tyrosine-705 of Stat3 were phosphorylated while Ha-ras was overexpressed. Interleukin-6 (IL-6)-induced phosphorylation of tyrosine-705 and serine-727, as well as DNA-binding and transcriptional activity of Stat3 were further enhanced by Ha-ras overexpression. In addition, overexpression of Stat3C in 7-4-Stat3C cells prevented the cells from morphological change and apoptosis triggered by the Ha-ras oncogene under serum-depleted conditions. We demonstrate that Ha-ras and Stat3 acting together synergistically induce Stat3 phosphorylation at serine-727 phosphorylation and cyclin D1 expression and further enhance transformation and tumorigenicity of the cell. Ha-ras-induced Stat3 phosphorylation at serine-727 plays a pivotal role in transcriptional activation of cyclin D1 and suppression of cell apoptosis. The effect of Ha-ras on Stat3 phosphorylation at serine-727 was also detected in human bladder (T24) and lung (H460) cancer cells. Stat3 phosphorylation at serine-727 is important in Ras-related tumorigenesis.

Original languageEnglish
Pages (from-to)131-139
Number of pages9
JournalDNA and Cell Biology
Issue number3
Publication statusPublished - 2009 Mar 1

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Genetics
  • Cell Biology


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